RSX type S egine

[tommyboy212]

I dont know that much about the VTEC and I was wondering why the type S really doesnt get its power until about the 5000 rpm range. I've been reading up on the car and alot of acticles seem to say this. Can someone explain. thanks.

 

[20ESGUY]

VTEC is a variable valve timing system which stands for something along the lines of Variable Timing Electronic Control (not excatly sure, but i thinks thats close). Basicly what it entails is two different sets of cam lobes on the same camshaft...intake and exhaust. The system will use a mild lift and duration lobe on both camshafts until a preset RPM limit is reached. Once the limit has been reached, in this case @ 5000, the system will physically switch to the other lobes which give a higher valve lift and longer duration. Basiclly it allows the best of both worlds...one cam that is very streetable and has its power ranges in the lower rpm scale and one cam that is not streetable and has its power ranges in the upper rpm scale.

 

[dmitrik4]

the new system in the K-series engines (i-VTEC) is much smoother and robust in the midrange than the VTEC in the old engines. if you look at a dyno graph of the RSX-S engine, the power curve is nearly linear, with very little jump @ the changeover point (~5600 rpm). torque, however, does jump a bit at that point. if you compare it to a dyno of, say, a Prelude engine, you can see the improvement in the power curve as the Prelude's curve jumps very suddenly at the changeover point. this lack of "jump" had led some people to believe that the old engines are eactually stronger (esp in the Civic Si), b/c the old engines were much louder thru the rev range and the cam switchover was so dramatic. in reality, the only difference is that the new engione pulls harder thru the midrange and therefore doesn't seem to have the top-end pull of the old motor.

that being said, you still definitely know when you've switched over in the Type-S.

 

[tommyboy212]

Thankx guys.